Concrete terms
Reinforcement is typically done with bars
#3 bars, #5 bars... number represents the diameter in 1/8ths of inches #n, n/8ths of inch..... #3 = 3/8ths of inch
shallow foundations
(spread foundations) are the type that transfer the building loads directly to the sufficient soil area.
5 ways to transport concrete to formwork
1. chutes 2. push buggies 3. buckets handled by cranes 4. pumping through a pipeline (pump truck) 5. Pneumatically forcing through a hose - shotcrete
Process of making portland cement
1. made of pulverized lime, silica, alumina and iron 2. mix limestone with clay, shale or slag 3. heat mixture to 2700° F 4. fuse mixture to make clinker (.75" rocks) 5. clinker pulverized with gypsum 6. powdery substance created
Compression strength of concrete range from
2500-19,000 PSI The structural engineer determines the compressive strength of the concrete If you have a light building the foundation doesn't need to be as strong as a steel building
How long do you have to deliver and discharge concrete at a building site
90 minutes for according to ASTM C94
Main specification for portland cement
ASTM C150
Air Entraining
Adding more air to the mix
ASTM
American Society for Testing and Materials
Steps of finishing concrete
Bleeding -water rising to the concrete's surface Screeding - moving a straightedge back and forth over surface Leveling - bringing concrete to the desired level Edging - smoothing the edge to prevent chipping Jointing Floating - Floating is done when the water sheen has disappeared and the concrete will support the weight of the finisher Troweling - Create a smooth surface
C-C
Center to center
Form Liners
Chosen by architect, because its an aesthetic element. Cast in place; you have to build the forms which takes time The exterior finish takes the finish of whatever the form work is made out of Permanent: you leave the form in place; the earth( grade beam), insulated concrete forms (IFC) Temporary: pull the form away; sidewalks, walls
Type 2 Slab on grade
Contains wire welded fabric + some reinforcing bars Resists some differential soil movement Minimum of 4" thick Ex: driveways, pool decking
Why does concrete need to be consolidated
Eliminate stone pockets and large air bubbles consolidate each layer with the previous embed reinforcing bring just enough fine material to the faces and top surfaces to produce the desired finish
ECC
Engineered Cementitious Composite (ECC), also called bendable concrete, is an easily molded mortar-based composite reinforced with specially selected short random fibers, usually polymer fibers.
insulating concrete forms
Great insulation, resist hurricanes and tornadoes, easy insulation from a concrete point of view, faster construction, fire resistant
Sitecast concrete
Heavy type of construction, slow to construct, transport the concrete to site
Four major types of precast concrete slab elements
Hollow core tongue and groove channel double tee
Bell bottom piers
It is a single unit (monolithic) and has far greater strength and stability than a column of connected or unconnected concrete pushed piles.
Is movement in buildings normal?
Its not a bad thing if the building moves, they just move. Want them to have a little bit of give Soils settle overtime Within reason it is normal
Advantages to precast concrete
Most homogenous concrete - made in controlled environment Control of quality materials and workmanship Good surface quality Superior strength Erection is fast Can erected in a variety of climates Faster construction time (compared to sitecast)
Type 3 Slab on grade
Reinforced and transfer superstructure loads Can resist changes in soils Designed by a professional engineer ex: grade beams
Type 4 slab on grade
Reinforced and transfer superstructure loads Is not designed to resist changes in soils MUST be designed by a professional engineer Supported by piers or piles
glass fiber reinforced concrete (GFRC)
Same concept as fiberglass; however glass fiber is embedded in Portland cement and sand (concrete mixture) Used for ornamental structures, wall cladding, and soffits Precast The glass fibers reinforce the concrete, much as steel reinforcing bars do in conventional construction. The glass fiber reinforcement results in a product with much higher flexural strength than normal concrete, allowing its use in thin-wall casting applications.
what determines the foundation type
Subsurface soil and groundwater conditions Structural requirements, including foundation loads, building configurations and depth Construction methods Environmental factors Building Codes
Post tensioning
The concrete is cast with a hollow duct or sleeve to encase the steel. After the concrete has cured, the steel is tensioned and anchored into place.
good foundations satisfy three requirements
The foundation must be safe. This means foundation do NOT fail (crack or break). The soil/rock on which the foundation sits must not fail. The foundation must settle properly. If the soil collapses or moves too much, the foundation will fail. The foundation needs to be selected properly to avoid adverse effects to surrounding property.
Type 1 Slab on grade - Ideal soil conditions
Usually 4" thick Carries no superstructure loads No reinforced but may contain wire welded fabric Rectangular in shape Ex: driveway, sidewalks, pad work
Where are vulnerable areas on buildings
When a material makes a 90° turn it is a weak point, or when you have a lot of a certain material. Every 20 ft of masonry you put a joint so they can move without cracking
flat slab
When the loads or spans required are larger, the flat slab systems is used. With this system, the slab thickness is increased where the slab sits on the column. In addition, the a 'capitol' is added to the top of the column to increase strength. For the flat slab systems, spans are generally 30 feet.
Types of Portland cement; Type 2
a little bit stronger than type 1, still considered normal
crawlspace
a rectangle of concrete
what is a mock up
a sample. largely aesthetic, can be very expensive
Super structure
above ground portion
Anchor Bolt
added to concrete before it dries to tie concrete to frame of building
Type A
air entraining,
Auger Cast Piles
also known as continuous flight auger piles (CFA), are deep foundation elements that are cast-in-place, using a hollow stem auger with continuous flights. The auger is drilled into the soil and/or rock to design depth.
superplasticizers
also known as plasticizers or high-range water reducers (HRWR), reduce water content by 12 to 30 percent. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction. The effect of superplasticizers lasts only 30 to 60 minutes and is followed by a rapid loss in workability. Added to concrete at the jobsite.
Control joints
are joints that "score" the concrete controlling where the crack will occur in the concrete. Sometimes called a saw cut. Controlling a weak point in the material
Why arent basements common in texas
because of water in the soil. Top soil is made out of clay, which expands and contracts with water...
Deformation patterns
better grip by increasing surface area. Helping secure the connection between steel and concrete
formwork; vertical boards
cleats
Compression
concrete is strong in this type of stress
Romans
considered the inventors of concrete
Expansion Joints
create a physical space within the concrete. You have a space between the material and you have a joint sealing material.
drop in elevation on plan
crescent moon looking thing
Carton Forms
designed to hold up the weight of fresh concrete long enough for the concrete to cure and support itself on piers or beams. Since it is a paper product, it absorbs the moisture of the surrounding soil and concrete and its supportive strength gradually diminishes
Clear concrete
developed by Hungarian Architect Aron Losonczi. during the mixing process, glass fibers are added to the traditional stone,
Steel in specs sheet
division 3
What division is concrete
division 3
Shop drawings
drawings produced by fabricators, sub contractors; EX: cabinet maker. in the case of concrete engineer approves shop drawings
Precast concrete
eans the concrete is formed and cured in a factory, transported to the construction site and erected as rigid components.
deep foundations
either piles or caissons), penetrate through upper layers on unstable soil to transfer the load to the strong soil or rock deeper within the earth.
corrosion-inhibiting admixtures
fall into the specialty admixture category and are used to slow corrosion of reinforcing steel in concrete. Corrosion inhibitors can be used as a defensive strategy for concrete structures, such as marine facilities, highway bridges, and parking garages, that will be exposed to high concentrations of chloride.
Three principle two way slab concrete systems
flat plate, flat slab, waffle slab
wind loads
force produced by the wind. Wind can push a building sideways (lateral), downward (push on the roof) and upwards (pull on the roof)
Types of Portland cement; Type 3
high early strength; only put so much weight on the concrete as you go. Concrete takes around 28 days to cure, if you use a different mix you can start having the strength earlier.
accelerating admixtures
increase the rate of early strength development, reduce the time required for proper curing and protection, and speed up the start of finishing operations. Accelerating admixtures are especially useful for modifying the properties of concrete in cold weather.
ICF
insulating concrete forms
wall footing/ strip footing
is a continuous strip of concrete that supports foundation walls
Column footing
is a square block of concrete with or without steel reinforcing that accepts the concentrated load placed on it from above by a building column
Pre stressed concrete
is applying a force to the steel before the concrete is poured.
Shear
is both types of stresses
tilt up construction
is casting a wall panel in a horizontal position and then tilting it to it final vertical position. Usually, these panels are solid, reinforced slabs five to eight inches thick. They have to be able to attach to the crane
concrete joist system
is comprised of concrete members usually spaced 26 or 36 inches apart, running in one direction, that frame into larger beams.
reinforced concrete
is the term used when steel is embedded in concrete, it increases the tension strength of the concrete.
what happens when concrete cures
it gives of heat (heat of hydration) and forms chemical bonds
One way system
l of the columns, beams and slab are poured in place; reinforced concrete. The reinforced steel is tied together at the junction between the columns and beams
substructure
livable below ground portion (basement)
which of these loads is highly subjective
live load
Types of Portland cement; Type 4
low heat; when concrete cures it gives off heat. When you have a lot of concrete you want the concrete to release the heat at a slower heat.
Precast concrete systems
means the concrete is formed and cured in a factory, transported to the construction site and erected as rigid components
Cast in place or site cast
means the concrete is formed and poured on the construction site. The concrete mixture must be transported to the site or mixed at the site
Coefficient of Thermal Expansion
measure in terms of inches and degrees F. For every degree that changes in Fahrenheit they measure how much the material moves in inches
specs
more detailed than plans/drawings.. organized like a book, organized by the construction specifications institute (CSI)
Types of Portland cement; Type 1
normal typical concrete. sidewalks, driveways, foundations for wood structures
Bearing capacity
of your concrete is essential to make sure that what you plan to have supported by the wall or slab will not be too heavy and cause it to crack and break
Fly ash
often used as a pozzolan to produce hydraulic cement or hydraulic plaster and a replacement or partial replacement for Portland cement in concrete production. Pozzolans ensure the setting of concrete and plaster and provide concrete with more protection from wet conditions and chemical attack.
OCEW
on center each way
Cast in place concrete structural systems can be classified into two general types
one way and two way systems
Foundation
part of the building that transfers loads to the soil
What two things are included in construction documents
plans and specs
Slab on grade foundation
popular in texas, Use the ground to create your form, dig in ground. Create a system of trenches, line it with plastic, then you pour your concrete in mold. Structural engineer decides the distances and grades of rebar.
Waffle slab
provides support for heavier loads at slightly longer spans (up to 40 feet). Waffle slabs are formed of prefabricated, reusable metal or fiberglass forms..
foundations are either
shallow or deep
Precast concrete elements
slabs, beams, girders, columns, wall panels
Tension
steel is strong in this type of stress
Precast categories
structural architectural
Types of Portland cement; Type 5
sulfate; for environmental. Resist elements
flat plate
the slab is designed and reinforced to span in both directions. Typical span is 25' in both directions
Mat slab foundation
the soil is so terrible, instead of trying to excavate.. You make one super slab, excavate several feet into the ground with one super thick reinforced slab
why do most foundations fail
they are put on bad soil
Chair
used to keep rebar elevated from touching the ground/surface
water reducing admixtures
usually reduce the required water content for a concrete mixture by about 5 to 10 percent. The treated concrete can have a lower water-cement ratio. This usually indicates that a higher strength concrete can be produced without increasing the amount of cement
Formwork; Horizontal boards
wales
Cast in place structural elements include
walls, columns, beams
Too much water will
weaken the concrete
Live Load
weight of the people, furniture, and equipment used by people, snow, ice and water on roof
Dead Load
weight of the structural system, the floors, roof, walls, MEP
retarding admixtures
which slow the setting rate of concrete, are used to counteract the accelerating effect of hot weather on concrete setting. High temperatures often cause an increased rate of hardening which makes placing and finishing difficult. Retarders keep concrete workable during placement and delay the initial set of concrete
